The present invention is directed, in general, to capacitors and, more specifically, to a capacitor having a dielectric layer including a Group 17 element and a method of manufacture therefor.
Capacitor arrays are currently one of the main building blocks for many high performance analog/mixed signal products like delta sigma analog to digital converters (ADCs), successive approximation register analog to digital converters (ADCs), pipeline analog to digital converters (ADCs), PGAs, precision reference switched analog filters, Codecs, etc. It is required, however, that the individual capacitors within these capacitor arrays be high precision capacitors. Recently, two parameters have been used to scrutinizes whether a certain capacitor meets the requirements required for use in one of the aforementioned capacitor arrays.
A first parameter tested to determining whether a certain capacitor meets the requirements to be considered a high precision capacitor is the capacitor""s voltage coefficient value. While an ideal capacitor""s capacitance is independent of the voltage being applied to it, those skilled in the art are aware that such capacitors are hard to come by. For this reason, the industry has developed a value to characterize how dependent a capacitor""s capacitance is upon the voltage being applied thereto, in other words a capacitor""s voltage coefficient value.
Turning to Prior Art FIG. 1, illustrated is a graph 100 plotting a specific capacitor""s capacitance value for a number of different voltages. By fitting a resulting curve 110 with an equation, a voltage coefficient value 120 may be obtained. The particular voltage coefficient value 120 resulting from the capacitor graphed in FIG. 1 is:
y=xe2x88x923.2047Exe2x88x9206x2+1.8522Exe2x88x9206x+1.0000E+00
As is noticed, the voltage coefficient value 120 has both a linear voltage coefficient value and a quadratic voltage coefficient value. It is desired that both of these values be as small as possible, and ideally equal to zero. Unfortunately, the voltage coefficient values currently achievable by conventional capacitors are often insufficient to meet the needs of the capacitor arrays mentioned above.
Another parameter those skilled in the art look to for determining whether a certain capacitor meets the requirements of being considered a high precision capacitor, is the capacitor""s dielectric absorption value. Ideal capacitors return to their original state after being charged and dissipated any number of times. However, such ideal capacitors are quite difficult to manufacture, and therefore are difficult to obtain. For this reason, the industry has developed a value to characterize the amount of charge that remains within a capacitor after the voltage has been removed, in other words a capacitor""s dielectric absorption value.
Turning to Prior Art FIG. 2, shown is a depiction 200 of three electrical situations 210, 220, 230 that a capacitor might experience. The first situation 210 is a situation where the capacitor is being charged. In the particular example shown, the capacitor is being charged using a 1 volt source (V0). The second situation 220 is a situation where the charged capacitor is being discharged. In an ideal scenario, the charge remaining in the capacitor after its discharged is zero. The third situation 230, however, illustrates an actual situation where a charge remains after the capacitor has been discharged. In the particular example shown, the remaining charge (V1) is about 1 mV. The capacitor""s dielectric absorption value may, then, be calculated by dividing the charge remaining in the capacitor (V1) by the source voltage (V0) applied thereto. As those skilled in the art are well aware, it is desired that a specific capacitor""s dielectric voltage value be as small as possible, and optimally zero. The dielectric voltage values currently achievable by conventional capacitors are, however, often insufficient to meet the needs of the capacitor arrays mentioned above.
Accordingly, what is needed in the art is a capacitor that has smaller voltage coefficient values or dielectric absorption values than those of the prior art.
To address the above-discussed deficiencies of the prior art, the present invention provides a capacitor, a method of manufacture therefor and an integrated circuit including the same. In one embodiment of the invention, the capacitor includes a first conductive plate located over a semiconductor substrate, wherein the first conductive plate has a second conductive plate located thereover. The capacitor, in the same embodiment, further includes a dielectric layer located between the first conductive plate and the second conductive plate, wherein the dielectric layer includes a Group 17 element.
The present invention alternatively provides a method of manufacturing a capacitor. In one embodiment of the present invention, the method of manufacturing the capacitor includes forming a first conductive plate over a semiconductor substrate, and placing a second conductive plate over the first conductive plate. The method further includes locating a dielectric layer between the first conductive plate and the second conductive plate, the dielectric layer including a Group 17 element.
The present invention further provides an integrated circuit including the capacitor. In addition to those features disclosed with respect to the capacitor, the integrated circuit includes transistors formed over or in the semiconductor substrate, as well as interconnects contacting the transistors and the capacitor to form an integrated circuit.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.